Electromagnetic relay



Dec. 12, 1961 w. DE FLIGUE ELECTROMAGNETIC RELAY 5 Sh 9 3d 55 sets Sheet 1 Filed Jan. 18, 1960 M m 0 Z M 7. mm on M M a L w J 2% Dec. 12, 1961 w. DE FLIGUE ELECTROMAGNETIC RELAY 3 Sheets-Sheet 2 Filed Jan. 18, 1960 INVE/VTo/x W Lo imiR .dc. FAj3Ue/ Dec. 12, 1961 w. DE FLIGUE ELECTROMAGNETIC RELAY 3 Sheets-Sheet 3 Filed Jan. 18, 1960 H m J. m M, M 0% M M a Uted States '1 atet 3,013,136 ELECTROMAGNETIQ RELAY Wladimir dc Fligu, 203 Rue dAulnay, Piessis- Robinson, Seine, France Filed Earl. 13, 1960, Ser. No. 2,927 Claims priority, application France Feb. 12, 1959 14 Claims. (Cl. 200-457 This invention relates to electromagnetic relay assemblies, particularly those of the type comprising a C-shaped magnetic core having centre leg with a magnetizing winding associated therewith, and having end legs each having a leg portion projecting generally normally from the centre leg and terminating in inturned polar portions formed with polar surfaces generally parallel to the centre leg, one of said polar surfaces (hereinafter termed the inner polar surface) facing towards said centre leg, and the other polar surface (termed the outer one) facing away from the centre leg. In such relays, the movable relay armature is in the form of a generally flat vane pivoted intermediate its ends about an axis transverse to the longitudinal direction of the centre leg of the core, and so arranged as to have portions of its opposite faces positioned in magnetic cooperation with the respective inner and outer polar surfaces. Thus, on energization of the magnetizing winding, the said portions of the opposite faces of the vane armature are attracted in opposite directions so that the armature is rocked about its pivot thereby to make and/or break any desired contacts that may be associated therewith.

Relay assemblies of the type just specified have yielded excellent results especially in that they permit of imparting a relatively large linear displacement to therelay contacts (associated with an end or each end of the vane armature) for a given length of the armature, and thereby providing a more positive andreliable contact-making and -breaking action even in smaliand miniature-size relays. However practical experience has shown that this type of relay is somewhat wanting in sensitivity and that the threshold of operation thereof is sometimes less than may be desired for certain applications.

It is an object of this invention to eliminate this difficulty and to provide a relay assembly of the specified type in which the sensitivity will be greatly enhanced and the operating threshold reduced to an extremely low value when so desired.

According therefore to an aspect of the invention, in a relay assembly of the type specified, the rocking armature is formed with an extension at one of its ends at least partially surrounding the related leg portion of the core to define therewith an auxiliary airgap of relatively small effective width throughout the rocking movements of the armature.

Owing to this permanently-present auxiliary airgap there is provided a pro-magnetization of the magnetic circuit comprising the core and armature, increasing the permeability of this circuit and correspondingly increasing the sensitivity. In other words, by suitably selecting the mean effective width of the auxiliary airgap provided according to the invention in relation to the mean effective width of the main airgap between the armature and polar surfaces ofthe core, it is possible to bring the permeability of the core material to an optimum range of values in which the attractive action of the polar surfaces upon the armature is considerably increased. Tests have shown'that for best results the said effective width of the auxiliary airgap should be in the range of from about one eighth to about four times the mean effective width of each of the main airgaps.

Another object of the invention is to provide an im hie 2 proved restoring or biassing arrangement in a relay of the specified type.

In attaining this object simultaneously with the foregoing one, according to another aspect of the invention, in a relay assembly of the type specified the rocking armature is formed with an extension at one of its ends circumventing and projecting longitudinally beyond the related leg portion of the core so as to define an auxiliary airgap therewith, and a permanent magnet is provided having a polar surface coacting with a face of said armature extension beyond said related core leg portion so as to cause the armature to be rocked in the reverse angular direction on deenergization of the magnetizing Windmg.

A further object of the invention is to provide improved means for the accurate positional adjustment of the relay contacts, which will be precise and convenient to operate while preventing inadvertent maladjustment in service from vibrations or other causes.

The above and further objects, aspects and features of the invention will become apparent as the disclosure proceeds, with reference to the accompanying drawings which illustrate an exemplary embodiment of the invention and wherein:

FIGURE 1 is a perspective view of a relay constructed according to the invention.

FIGURE 2 is a longitudinal section on line 11-11 of FIGURE 3.

FIGURE 3 shows the relay in plan.

FIGURES 4 and 5 are end views from the respective ends of the relay.

FIGURE 6 is a simplified plan View of a contact supporting member, and

FIGURE 7 is a view on line VII-VII of FIGURE 6.

The relay assembly illustrated comprises an insulating frame in the general form of a. spool including a recessed or tubular central section In of rectangular cross section and two relatively thick recessed end flanges 1b and 1c. Wound about the central or body section 1a is an energizing coil winding 2 having the protruding ends 2a and 2b adapted in service to be connected with a source of operating voltage.

The relay assembly further includes a C-Shaped magnetic core generally designated 3, and made in two sections 3a and 3b mating with each other along a slanting plane 4. In assembling the relay, the coil 2 is first wound around the body section of the frame 1, and the two sections 3a and 3b of the core are then inserted through the recesses in the respective end flanges 1b and 1c and into the recess in the tubular mid-section 1a and are pushed into engagement with one another along the mating plane 4. Owing to the low angle of slant of this plane with respect to the longitudinal axis of the frame, the core sections 3a and 3b tend to become firmly wedged against each other. In order further to ensure a strong assembly, the two core sections 3a and 3b may be bonded to each other within the frame by coating the mating surfaces thereof with a suitable adhesive, preferably an epoxy resin such as that sold by the trade name Araldite.

The provision of a core 3 in two sections mating along a slanting plane in the manner described not only facilitates assembling operations without substantially detracting from the strength of the final assembly, but has the further advantage of introducing an increase in reluctance of the core which will minimize or prevent any tendency of the core to adhere to the vane of the relay by residual magnetism in the deenergized condition.

As is clearly apparent from FIGURE 2, the C-shaped core 3 is dissymmetrically formed at its opposite tapering ends having a larger end leg 3d at one end and a smaller end leg 30 at the other. A flat armature strip or vane pivoted at an intermediate point by means of opposed pivot pins 5a in bearings 6 of the fixed structure of the relay as later described, has portions of its opposite faces cooperating respectively with an inner polar surface of the larger end leg 3d to determine an airgap H therewith, and with an outer polar surface of the smaller leg 30 to define an airgap H therewith, both airgaps H and H being substantially equal in width in' the neutral position of the vane 5 about its pivot, as

shown in FIGURE 2. The vane 5, as stated above, is

journalled by way of its pivots 5a in the bearings 6 which are preferably ball bearings of very small size. The bearings 6 are mounted in respective elongated side strips 7 and 8 extending in parallel spaced relation along the sides of the relay assembly between the end flanges 1b and 1c. The side strip 8 in the construction shown has its ends secured by way of screws 9 to the respective end flanges 1b and 1c, while the side strip 7 is secured to said flanges by screw studs 21. Each screw stud 21 carries a hexagonal portion 22 fixedly secured or formed on it intermediate the ends of the stud, one side of the portion 22 presenting a frustoconical surface 22a (see FIGURE 3), and each stud has threaded end parts projecting from the opposite sides of the portion 22. One end of each stud 21 is screwed into a threaded hole formed in a side of the related end flange lb or 10, so as to clamp the side strip 7 thereagainst by action of the frustoconical surface 22a against a complementary surface formed in an opening of the strip. The other threaded end of each stud 21 protrudes outwardly from the side of the relay assembly. Such protruding ends of the studs 21 may be used for mounting the relay by means of nuts 24 upon a supporting structure, as shown in dot-and-dash lines 23 in FIGURE 3.

As shown in FIGURE 1, the frame side member or strip 7 has an extension 711 at one of its longitudinal ends, serving for the attachment of a current input lead, for

which purpose an eyehole is shown formed in said extension. The side strip 7 is further shown to be electrically connected to the vane 5 by means of a short length of flexible wire 10 soldered at its ends to the strip 7 and vane 5 preferably in small holes or depressions formed in the respective elements. By this means current can be applied to the vane without having to be led in through the bearings 6, and thus avoiding the diff culties usually accompanying the application of electric current through bearings.

Secured to the outer surface of end flange 1c are the two contact supporting members or brackets 11 and 12 (see FIGURE 4), mounted by screws 13 and 13 in a manner to be more fully described later. The brackets 11 and 12 are provided in the form of suitably bent strips and each carries at the free end of a protruding arm of it a related contact element 11a or 12a, which contact elements cooperate with the respective contact elements 14 and 15 mounted at the adjacent ends of the vane 5 on the under and the upper face of the vane respectively.

Secured on the outer face of the other end flange 1b (FIGURE 5) is the magnetic restoring assembly, comprising a small permanent magnet block 17 held in position by means of a bracket 18 secured to the end flange by screws 19.

The plan contour of the vane armature 5 is apparent from FIGURE 3 whence it is seen that the end of the vane towards the end flange 1b is cut out in the shape of a hook so as to circumvent. the vertical or upstanding portion of the leg 3d of core 3, and project beyond said leg at 5b, this end extension portion 5b overlying the restoring magnet block 17 as shown in FIGURE 2.

As shown in FIGURE 5, the top of the end flange 1b is cut out to receive the hook-like extension 5b of the vane armature. In view of the presence of such cutout, the side strip 8 is formed with an enlarged square end portion 8a, whereby the screw 9 serving to secure 4 that end of the strip 8 is able to engage the flange 1b in a part thereof that is not weakened by the cutout.

As previously mentioned the flanges 1b and 1c are recessed to receive the upstanding legs of the core 3 and they are provided thick enough to allow the contacts 11, 12 and the magnet 17 to be'supported from said end flanges at positions beyond the said upstanding core legs.

In operation, when current is applied to the magnetizing winding 2 by way of the terminal ends 2a, 2b, it will be understood that the opposite ends of armature 5 are respectively attracted towards the outer and inner polar surfaces respectively formed on the legs 3c and 3d of the core 3. Thus the attractive forces form a couple which rocks the vane 5 to engage the contacts 14 and 11a. Conversely, when the current is cut off, the permanent magnet 17 is allowed to act on the projection 5b of the vane, to rock the vane 5 in the reverse direction about its pivot and restore the contacts 12a and 15 into engagement.

The contact support brackets 11 and 12 are substan tially rigid so as to limit the rocking movement of the vane positively in each direction on engagement of the respective contacts, so that an airgap is provided in all conditions of the relay; in the idle or deenergized, condition the airgap is present between magnet 17 and armature extension 5b, and in the operated or energized condition airgaps are present between the opposite ends of the armature 5 and the adjacent polar surfaces of the core legs 30 and 3d. Thus, on energization of the relay the later two airgaps are both active. Moreovensince the vane is then parallel to the general axis of the relay winding and is pivoted substantially at the centerof its length, the two lever arms on which the opposite attractive forces are applied are equal, and are of relatively large value. Consequently, even with a comparatively low number of magnetizing ampere-turns, the rocking couple'available is large. Furthermore, owing to the large leverages acting on the vane, even when the angular range of vane movement is small, the linear range of movement of the displacement of the vane between the contacts 11a and 12a is quite large, so that positive and reliable contact closing and opening actions are provided.

It will be noted that the magnet 17 acts on the extension 5b of the vane by one magnetic pole only. Positional adjustment of the magnet 17 with respect to the vane extension 5b provides a means of adjusting the restoring or biassing force. If desired, appropriate magnetic inserts may be provided for magnetically shunting the strip 17,, so as to weaken the bias force, thereby allowing a closer spacing between the vane extension 5b and the magnet and increasing the suddenness and positiveness of relay operation.

As will appear from FIGURE 3, the inner end surface 27 of the recess defined by the hooklike armature extension 5b partly surrounding the core leg 3b lies very close to the surface of that leg, defining therewith a relative narrow auxiliary airgap whereby the magnetic flux is partly shunted, and thus reducing the reluctance of the magnetic circuit comprising the core, armature and active airgaps. If e is the average distance between the core leg and the interior of the hook extension of the vane, which average distance may be defined as /s(e +e +e using the symbols indicated in FIG- URE 3, then the value e should preferably lie within the range from one-eighth to four times the mean value of the main airgaps H and H formed between the vane and the end legs of the core. a

With the above arrangement, when the winding 2 is energized, the entire magnetic circuit of the relay is magnetized and the magnetization is increased owingto the shunting of the field through the auxiliary airgap, thereby rapidly increasing the permeability of the magnetic circuit so that, as the energizing current is increased in the faces of the core legs 30 and 3d quickly reaches a value suflicient to attract the vane 5.

In other words the operating threshold of the relay is more rapidly attained due to the magnetic fiux shunting action of the auxiliary gap. It has in fact been found possible to construct a relay of very small dimensions, e.g., only 30 mm. long and x 15 mm. in transverse section, requiring a power of less than one milliwatt for operation.

The pivotal mounting of the armature substantially about its axis of symmetry facilitates the construction of relays wherein the armature is balanced both statically and dynamically.

As shown in FIGURES 6 and 7, in the end flange 1c of the frame there are formed threaded holes 25 for the respective contact supporting brackets 11 and 25, in which screws 13 and 13 with conical heads 13a are engaged for securing the respective brackets 11 and 12. The screws extend through an opening 26 in the respective bracket 11 or 12, the ends of which opening are engaged under the conical heads 13a of the screws. The said ends 26a and 26b of the opening or slot 26 are arcuate with a radius of curvature substantially equal to the larger end radius of the frustoconical surfaces 13a. The distance d between the ends 26a and 26b is less than the distance D between the remotest points of the opposite edges of the frustoconical heads 13a, but greater than the distance E between the remotest points of the screw threads of screws 13 and 13 In the position shown in FIGURES 6 and 7, the screws 13 and 13 are assumed to be engaged to equal depths in the holes 25 and, moreover, the opposite edges 26a and 26b are in engagement with said screws, thereby holding the contact supporting bracket in position. If screw 13 is screwed out while simultaneously screw 13 is screwed further into the frame by an equal amount, the contact bracket is caused to slide along the frame 1 in the direction towards the latter screw 13 (rightward in FIGURE 6), and when both edges 26a and 26b have again been restored into engagement with the frustoconical surfaces 13a the bracket is again blocked in position.

The end positions of the bracket 11 or 12 are provided by abutment of one of the edges 26a or 26b against the thread of the corresponding screw 13 or 13 when the head of the screw is completely disengaged to clear the opening 26, while the other screw is at such time fully sunk into its hole, and the opposite edge of the slot 26 is in engagement with the periphery of the corresponding conical head 13a.

Thus it is seen that the maximum possible displacement of the bracket 11 (or 12) with respect to the frame 1 will be obtained when the height dimension of the conical portions 13a equals twice the thickness of the contact bracket and, moreover, the distance between the ends 26a and 26b of the slots equals the distance L between the remotest point of the thread of one screw and the remotest point of the edge of the frustoconical head of the other screw.

The heads of the screws 13, and 13 are formed with coaxial cylindrical portions 13b surmounting the frustoconical portions 13a, and the distance between the axes of the threaded holes 25 is made equal to the diameter of each such cylindrical part 13b. Thus the two cylindrical parts 13b will be constantly in contact engagement pro vided their height is made at least equal tothe thickness of the contact brackets. The screw driver kerfs 130 are for-med in these cylindrical head portions. When both screws are clamped to block the bracket, should either screw tend to come loose, it will at the same time tend, by way of the contact engagement between the parts 13b, to turn the other screw in the sense tending to clamp 1t tighter, which is impossible if the screws are properly screwed home. Thus the two screws act to block one another and spontaneous loosening by vibrations is prevented. The friction between the screw head portions 13a should not, however, be such as to prevent voluntary rotation of one of the screws without rotating the other. If desired, however, the friction be sufiiciently hard to require the use of two screw drivers (or other tools) for rotating one screw while the other is held blocked.

In the construction shown, the concave ends 26a and 26b of the slots are shown normal to the surfaces of the contact bracket. However such ends may be made chamfered so as to conform to the frustoconical shape of the screw heads at 13a.

Various other modifications may be made in the details of construction shown and described.

What I claim is:

1. In a relay assembly including a C-shaped magnetic core having a central leg with a magnetizing winding thereon and two end legs each including a leg portion generally normal to said central leg and an inturned polar portion with an active polar surface, one of said polar surfaces facing towards and the other facing away from said central leg, and a vane armature pivoted intermediate its ends about an axis transverse to said central core leg and having portions of its opposite faces arranged for magnetic cooperation with the respective polar surfaces, whereby energization of said magnetizing winding will attract said opposite face portions of the vane armature towards said respective polar surfaces to rock the armature about its pivot axis in one angular direction, and restoring means for rocking the armature in the opposite direction, that improvement comprising: said vane armature formed with an extension at one end thereof at least partially surrounding and projecting longitudinally beyond a related leg portion of the core to define therewith an auxiliary airgap of relatively small effective width throughout the rocking of the armature.

2. In a relay assembly including a C-shaped magnetic core having a central leg with a magnetizing winding thereon and a first and a second end leg respectively including first and second leg portions generally normal to said central leg and inturned tapering polar portions respectively having an inner and an outer polar surface, the inner surface facing towards, and the outer surface facing away from, said central leg, and an armature pivoted intermediate its ends about an axis transverse to said central core leg and having portions of an outer and an inner one of its opposite faces arranged for magnetic cooperation with said inner and outer polar surfaces respectively, whereby energization of the winding will rock the arma ture in one angular direction, that improvement comprising: said armature extended so as at least partially to surround and project longitudinally beyond said first leg portion, and a permanent magnet element having a polar surface cooperating with another portion of said inner face of the extended vane armature beyond said first leg portion so as to rock the armature in an angular direction reverse from said one direction on deenergization of the winding.

3. In a relay assembly in combination, a C-shaped core having a central leg and end legs the latter respectively including leg portions projecting generally normally from said central leg and inturned tapering polar portions respectively having an inner and an outer polar surface facing respectively towards and away from said central leg; a vane armature pivoted intermediate its ends about an axis transverse to said central leg, having portions of an outer and an inner one of its opposite faces defining variable airgaps with said inner and outer surfaces respectively and having an integral extension at one end of said armature so as at least partially to surround a related one of said leg portions and define therewith a substantially constant auxiliary airgap; magnetizing winding means inductively associated with said core whereby energization of the winding means will rock the armature in one angular direction and, restoring means for rocking the armature in the opposite angular direction on deenergization of the winding.

4. The relay assembly claimed in-claim 3, wherein said auxiliary airgap has a mean effective width within a range of from about one eighth to about four times the average width of each of said variable gaps.

5. The relay assembly claimed in claim 3, wherein said armature extension is substantially hook-shaped so as to surround said leg portion on substantially three of the four sides thereof.

6. The relay assembly claimed in claim 3, wherein said armature extension at least partially surrounds the leg portion adjacent said inner polar surface and projects therebeyond, and said restoring means comprise a permanent magnet means magnetically cooperating with the projecting portion of said extension on the same side therefrom as said central leg.

7. A relay assembly as claimed in claim 13 further comprising a frame structure including a recessed central part surrounding said central core leg and recessed end flanges partially surrounding said leg portions, said winding being supported about said central part of the frame, parallel spaced side members each having opposite ends attached to the respective end flanges, and pivot bearing means at registering positions on said side members for pivotally supporting said armature.

8. A relay assembly as claimed in claim 7, wherein said G-shaped core member is in two parts mating along a slanting plane of said central leg within said recessed central part of the frame.

9. In a contact-making relay assembly having a stationary structure including a magnetizable core and a movable structure including an armature magnetically coacting with said core, and at least one pair of contacts respectively supported from said fixed and movable structures for relative movement between closed and open conditions on movement of said armature consequent on coaction thereof with said core, means for adjustably supporting one contact of said pair from said fixed structure comprising, a plate member slidable over a surface of said fixed structure, an opening in said plate member, a pair of spaced threaded holes in said fixed structure surface within the boundaries of said plate opening, and a pair of screws adjustably engageable in said threaded holes, said screws having frustoconical surfaces respectively coaxial therewith and adapted for engagement with those edges of the opposite end walls of said opening at the surface of the plate facing away from said fixed structure, whereby concurrent and reverse rotational adjustments of said screws will constrain said plate member to slide over said surface for positional adjustment of said one contact.

10. An assembly as claimed in claim 9, wherein said opposite ends of the plate opening are arcuate with a radius of curvature substantially equal to the maximum radius of said frustoconical surfaces.

11. An assembly as claimed in claim 9, wherein said frustoconical surfaces are substantially equal in axial dimension to twice the thickness of said plate member, and wherein the distance between said opposite ends of the opening engaged by said frustoconical surfaces'is substantially equal to the distance from the side of the thread of one screw remote from the other screw to the side of the larger base of the frustoconical surface of said other screw remote from said one screw.

12. An assembly as claimed in claim 9, whereinsaid screws include cylindrical surfaces coaxialwith said respective frustooonical surfaces and adapted for mutual frictional engagement throughout the range of said rotational adjustment of the screws.

13. A relay assembly comprising a C-shaped core having a central leg and end legs respectively including one long and one short leg portion laterally projecting from the central leg and inturned tapering polar portions respectively having an inner and an outer polar surface facing respectively towards and away from said central leg; a magnetizing winding on said central leg; a vane armature pivoted intermediate its ends and intermediate said leg portions about an axis transverse to said central leg, said armature magnetically cooperating with said inner and outer polar surfaces .for rocking towards said surfaces and having an extension formed at that end thereof cooperating with the said inner polar surface to surround at least partially the said long leg portion of the core and define a substantially constant auxiliary airgap with the said leg portion; restoring means for rocking said armature away from said inner and outer polar surfaces; one contact member on each face of said vane-armature at the end thereof remote from said extension; and one steady contact cooperating respectively with each of said former contact for limiting rocking of the armature in either direction.

14. A relay assembly according to claim 13, wherein said restoring means comprise a permanent magnet having at least one polar surface directed towards the projecting part of said extension and further comprising an insulating frame including a recessed central part surrounding said central core leg and recessed end flanges partially surrounding said leg portions, said winding being supported about said central part of the frame; and means for securing said permanent magnet on the said flange surrounding the said long leg portion and means for securing both said steady contacts on the said flange surrounding the said short leg portion.

References Cited in the file of this patent Angold Sept. 1, 1959 

